The effects of hydrogen incorporation into -Ga2O3 thin films have been investigated by chemical, electrical and optical characterization techniques. Hydrogen incorporation was achieved by remote plasma doping without any structural alterations of the film; however, Xray photoemission reveals major changes in the oxygen chemical environment. Depth-resolved cathodoluminescence (CL) reveals that the near-surface region of the H-doped Ga2O3 film exhibits a distinct red luminescence (RL) band at 1.9 eV. The emergence of the H-related RL band is accompanied by an enhancement in the electrical conductivity of the film by an order of magnitude. Temperature-resolved CL points to the formation of abundant H-related donors with a binding energy of 28 ± 4 meV. The RL emission is attributed to shallow donor-deep acceptor pair recombination, where the acceptor is a VGa-H complex and the shallow donor is interstitial H. The binding energy of the VGa-H complex, based on our experimental considerations, is consistent with the computational results by Varley et al.

Nitrogen (N) is a promising candidate currently being pursued for p-type doping in Ga2O3. In this work, the results of detailed investigations into N-doped β-Ga2O3 nanowires using microstructural, chemical, and optical analyses are described. Monoclinic β-Ga2O3 nanowires are grown by chemical vapor deposition using a metallic gallium (Ga) precursor and subsequently doped with N by remote plasma by exploiting their nanoscale cross sections and large surface-to-volume ratios. The N incorporation into β-Ga2O3 is confirmed by X-ray absorption near-edge and Raman spectroscopies without changes in the nanowire morphology. N is found to exist mainly as molecular N2 and N–O chemical states, but a significant portion of N substitutes on oxygen (O) sites. Concurrent temperature-resolved cathodoluminescence measurements of the undoped and N-doped β-Ga2O3 are used to track the temperature dependences of their intrinsic ultraviolet (UV) luminescence and defect-related visible bands from 80 to 480 K. The blue and green bands increase in intensity relative to the UV after N doping; however, their intensity variations with temperature are found to be identical for the undoped and N-doped β-Ga2O3, indicating that these bands originate from existing recombination pathways in Ga2O3 rather than from radiative N-related centers. The enhancement in defect-related luminescence in N-doped β-Ga2O3 is explained by an increase in the concentration of O vacancies as a result of the compensation of NO acceptors.

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